Sodium Benzoate
Sodium benzoate · INCI Sodium Benzoate
If you have looked sodium benzoate up, you have probably read something alarming about benzene. That story comes from soft drinks, and the reaction behind it needs added vitamin C, which our products do not contain.
You may have read that this turns into benzene. There is a real story behind that, and it does not apply to our products.
What it is
Sodium benzoate is the sodium salt of benzoic acid. Ours is manufactured. Benzoic acid also occurs naturally in some fruits, such as cranberries, but ours is not taken from fruit.
Two things keep each bottle sound. The first is the preservative, a ready-made blend of sodium benzoate and gluconolactone. Sodium benzoate does the preserving, and gluconolactone helps it work. The second is the pH. Sodium citrate buffers the cream at pH 5 to 5.5, close to the skin's own. At the end of making, the pH is checked and fine-tuned with a little sodium hydroxide or citric acid.
We chose sodium benzoate because it is well tolerated and permitted as an ingredient under organic cosmetic standards. It works best in a mildly acidic product, which is one reason the pH matters.
Every preservative restrains microbes to some degree, so we chose one with a light touch. In a laboratory skin model, two of the blends containing sodium benzoate held back Staphylococcus aureus while sparing S. epidermidis, the skin's main beneficial resident. In studies on people, finished products made with common preservative systems left the variety of skin bacteria unchanged over several weeks. Our exact system has not been tested on skin, but the research suggests preservation of this kind has little effect on the skin microbiome.
What it does in our formulas
Sodium benzoate keeps the product free of bacteria and mould, working with gluconolactone.
It keeps the product free of bacteria and mould
Sodium benzoate works with the gluconolactone further up the list, at the mildly acidic pH that sodium citrate holds, pH 5 to 5.5, to make the product inhospitable to bacteria and mould. It is well tolerated and permitted as an ingredient under organic cosmetic standards, which is a large part of why we chose it.
Well characterisedWhat the research does not show
Two things get said about sodium benzoate. One is a real story taken out of context. The other, that preservative-free is safer, gets the risk the wrong way round.
Marketed as It turns into benzene, which causes cancer
Marketed as Preservative-free products are safer
On the label and in the range
Sodium benzoate appears in every one of our formulations, toward the end of the ingredient list, and it works with the gluconolactone sitting further up. The exact percentage is published on each product page, as it is for everything we use.
Is it suitable for me?
Sodium benzoate has been reviewed by the independent expert panel that assesses cosmetic ingredients and found safe as used. It is well tolerated, suits a vegan routine, and is permitted as a preservative under UK and EU cosmetic law, within set maximum levels. Allergic reaction to it is uncommon, though as with any preservative it is possible, so if your skin reacts easily a patch test first is sensible.
As with anything new, if your skin reacts easily it is worth patch testing first.
The research behind this page
We review the published literature. We do not conduct the studies below.
- Nair B. Final report on the safety assessment of benzyl alcohol, benzoic acid, and sodium benzoate. Int J Toxicol 2001;20(Suppl 3):23-50. →
- Johnson W, Bergfeld WF, Belsito DV, et al. Safety Assessment of Benzyl Alcohol, Benzoic Acid and its Salts, and Benzyl Benzoate. Int J Toxicol 2017;36(3 Suppl):5S-30S. →
- Pinto D, Ciardiello T, Franzoni M, et al. Effect of commonly used cosmetic preservatives on skin resident microflora dynamics. Sci Rep 2021;11. →
- Murphy B, Hoptroff M, Arnold D, Eccles R, Campbell-Lee S. In-vivo impact of common cosmetic preservative systems in full formulation on the skin microbiome. PLoS One 2021;16:e0254172. →